Furnace roller



April 12, 1960 w, H, DAlLEY, JR" ETAL 2,932,497

FURNACE RLLER Filed NOV. l5, 1955 INVENTUR.

. ul hf. Dfi/LEY, Je.

7 di vgne E@ (d, l "J 2,932,497. Patented Apr. 12,v 1960 United 4States Patent Oce FURNACE ROLLER William H. Dailey, Jr., and William A. Phillips, Toledo, Ohio, and John W. Carter, Providence, R.I., assgnors, thy mesne assignments, to Midland-Ross Corporation, Cleveland, Ohio, a corporation of Ohio Application November 15, 1955, Serial N o. 546,962

'4 Claims. (Cl. 26S- 6) This invention pertains to a roller for utilization at elevated temperatures and is particularly adapted for use in a furnace.

The use of rollers as, or as part of, a furnace conveying system has always been accompanied by problems of expansion, lubrication, and proper alignment. As the rollers expand, due to the higher temperatures to which they are subjected, a substantial linear expansion occurs, the amount depending on the material, length, and temperature. Such occurrence may cause the bearings to become misaligned or the roller to bind on the furnace casing.

Lubrication of the bearing surfaces of the roller is frequently diilicult due to the heat absorbed by the roller being conducted to that portion adjacent the bearings. These resultant elevated temperatures cause the lubricating material to break down or harden and thus prevent proper lubrication. This heat may also cause suicient expansion in the bearing area to produce seizing which may produce enough friction to stop rotation of the roller.

`Furthermore, when the bearings are attached to the furnace casing, slight movement and warping of this casing causes rnisalignment of the rollers. Precise alignment is essential in many instances such as in a strip furnace where strips of metal being heat treated are passed over the rollers. In this case, a slight misalignment will cause the strip to stretch or be directed to one side in which case jamming in the furnace is likely to occur.

In view of these problems, an improved roller has been devised that adequately compensates for linear eX- pansion, maintains the bearing area at relatively low temperatures, and prevents misalignment from occurring.

For further consideration in what is novel and my invention, refer to the accompanying drawing and subsequent specification.

In the drawing:

Figure l is a partially sectional view of a roller embodying the invention,

Figure 2 is a detailed view of a portion of Figure l, and

Figure 3 is a partially sectional view of a portion of a furnace embodying the invention.

Roller consists of an elongated cylinder 11 with conical-shaped, tapered ends 12 and 13 welded thereto. Ends 12 and 13 consist of flanges 14 and 15, sharply tapered portions 16 and 17, and gradually tapered portions 18 and 20. Cylinder 11 extends past anges 14 and to provide a wider surface than otherwise possible that can extend from one wall of the furnace to the other, if desired. Ends 12 and 13 are filled with castable refractory insulation 21 and 22 which decrease heat transfer to shafts 23 and 24 which bearing 25, and a similar one at the other end, contact. Bearing 25 is supported by wall 45 in turn attached to rigid member 26 which is separate from furnace wall 27 that comprises a metal casing 28 and refractory 30. Metallic radiation shields 31 and 32 consisting of alloy sheets are placed in front of insulation 21 and 22 and are aixed to anges 14 and 15. Additional metallic radiation shields 33 and 34 are placed around the surfaces of portions 16 and 17, and may be tack or plug welded thereto in a manner to leave a slight space between the shields 33, 34 and the portions 16, 17. These decrease the amount of heat radiated from adjacent surfaces 19 of the refractory wall to these portions. Such heat is considerable since the two bodies are adjacent and the refractory temperature is close to the temperature within the furnace chamber. Metallic radiation shields 35 are also placed in annular recess 36 to decrease outward radiation of heat. Metal bellows 37 extends from recess 36 to member 26 to form an effective seal for atmosphere in the furnace. A similar assembly is constructed about the other end of the shaft.

` Bearing 25 and the one at the other end support, shafts 23 and 24 on surfaces or journals 38 and 40. Portions 41 and 42 of these journals are undercut to form grooves with two or three wraps 50 of aluminum foil or similar material being placed about these portions. The foil then serves as radiation shields and decreases heat transfer from the shafts to the bearings. As an alternate, the groove may be formed on the inner surface of the inner race of the bearing with the foil placed in this groove.

-In some situations an atmosphere containing a high percent of hydrogen may be used in the furnace. It has been discovered that such an atmosphere tends to inltrate through the furnace rolls and into the volumes defined by the rollers. A combustible mixture may thus be formed with the air therein and creates a formidable explosion hazard, particularly in the larger size rolls. To prevent this, means for purging the roller have been developed. Passages 43 and 44 are thus provided through radiation shields 31 and 32, refractory 21 and 22, and shafts 23 and 24. About the bearing 25 and shaft 24, a wall 45 is placed which is gas-tightly aixed to member 26. This is provided with an end plate 46, a grease iitting 47 to lubricate the bearing, and a gas inlet 48. Bearing 25 slides outwardly along wall 45 with shaft 24 as the roller expands. An inert gas is then emitted through inlet 48 to the chamber defined by wall 45 and plate 46 and then flows through passage 44 and into the volume within the roller. From here it Hows through passage 43 and is vented into the air, an exhaust manifold, or the like. The temperature of the bearings has been decreased from over 600 F. to 200 F. by the use of these methods.

To further decrease roller temperature, radiation shields 61, 62, 63, and 64 are placed in the furnace chamber between radiant tubes 65 and the rollers 10 as shown in Figure 3. These may be made of single alloy plates or two or more plates with refractory placed therebetween. They are counterweighted or suspended above their centers of gravity, by pivotable rods 66, 67, 68 and 70 which extend laterally across the furnace chamber and are supported by the casing. This methodof suspension permits the shields to swing if a splice or other projection on strip 71 should hit them, thus allowing them to be safely placed closer to the strip. The temperature about rollers 10 is maintained as low as l350 F. by the use of the shields when the temperature in the heating chamber Ais l750 F. This temperature is low enough to eliminate the necessity of continuously rotating the rollers to prevent sagging during a line stoppage. The radiation shields also maintain the temperature of the rollers closer to that of the strip 71 and reduce relative slipping between the two.

The disclosure has been intended to serve -in an illustrative and not a limiting sense. Various modifications may be incorporated without departing from the scope of the invention as delined in the appended claims.

We claim:

1. In a furnace having wall means defining a heating chamber and heating means within said chamber, a roller displaced from said heating means for supporting work passing through the chamber comprising, in combination:

elongated cylinder; conicalshaped ends attached` to' both lends-df said cylinder; shafts extending outwardly from said conical-shaped ends, said shafts being in axial alignment with the'axis oflsaid cylinder; insulation filling theA volume defined by said/ends; circular'radiation shields in front of said insulation, perpendicular to the axis of said cylinder; second radiation shields around portions of said ends adjacent said cylinder and loosely attached thereto; surfaces on each shaft adapted to be received in a bearing, a center portion of each sur-face being undercut and forming an annular groove; foil located around said undercut portions; a passage through cach of said shafts, insulation, and circular radiation shields; means for emitting gas to one of said passages; means in the (furnace wall forming anV annular recess around each of said ends; third radiationshields in the rece-ss extending closely to the surfaces o fsaid' ends and being perpendicular to the axes thereof; and'fourth radiation shields disposed between said heating means and said roller for decreasing heat transfer from the former tothe latter.

2. In a furnace having refractory walls defining a heating chamber, a roller for supporting work passing through the furnace and comprising, in combination: an elongated cylinder; conical-shaped ends attached to both ends of said cylinder; shafts extending outwardly from said conical-shaped ends, said shafts being in axial alignment with the axis of said cylinder; insulation filling the volume defined by said ends; circular radiation shields in front of said insulation, perpendicular to the axis of said cylinder; second radiation shields around portions of said ends adjacent said cylinder and loosely attached thereto; surfaces on each shaft adapted to be received in a bearing, a center portion'of cach :surface being undercut and forming an annular groove; foil located around said undercut por tions; a passage through each of said shafts, insulation, and circular radiation shields; means for emitting gas to one of said passages; means in the furnace wall forming an annular recess around each of said ends; and'third radiation shields in the recess extending closely to the surfaces of said ends and being perpendicular to the axes thereof.

3. A roller for supporting and guiding strip to be heat treated in a strip heating furnace comprising, in cornbination: an elongated cylinder; conicallrshaped ends concentrically attached to both ends of said cylinder; shafts extending outwardly from said conical-shaped ends, said shafts being in axial alignment with the axis of said cylinder; insulation filling the volume defined by said ends; circular radiation shields in front of said insulation, perpendicular to the axis of said cylinder; radiation shields around portions of said ends adjacent said cylinder and loosely attached thereto; surfaces onV each shaft adapted to be received in a bearing, a portion yof each space being undercut; foil located around said. undercut portions;l a passage through each of said shafts, insulation, and circular radiation shields; and means for emitting gas to one A of said passages.

4. A roller for a furnace chamber for supporting work passing therethrough comprising: an elongated cylinder; conical-shaped ends concentrically attached to both ends of said cylinder and adapted for extending through opposite walls of the furnace chamber; radiation shields, attached to that portion of said conical-shaped ends-y adapted to be within the furnace chamberV and adjacent the furnace walls; surfaceson said conical-shaped: endsj adapted to receive bearings, a center portion of each surf face being undercut and forming an annular groovetand,

foil located in said groove.

References Cited in the file of this patent UNITED STATES PATENTS 61,401 Collins Jan. 22, 1867 420,951 Millhauser Feb. 11, 1890-` 'l,087,529 Corin Feb. 17, 1914; 1,361,977 Fuller Dec. 14, 1920* 1,657,212 Hitchcock' Jan. 24, 1928; 1,763,689 Drake June 17, 1930; 1,788,977 Blockinger Jan.`13'193 1 1,820,074 Kilborn Aug.- 25, 1931. 1,840,661 Fahrenwald Jan. 12, 1932 1,944,217 `Carpenter et al Jan. 231934'1l 2,045,773 Havey` June 30, 19362 2,100,222 McFarland Nov. 23, 1937 2,449,662 Leeson Sept. 21, 19482Y 2,603,578 Ornitz July 15, 1952V 2,664,282 Mann Dec. 29, 1953:, 2,788,957 Lindquist Apr. 16, 1957 

